Page:The Kinematics of Machinery.djvu/457

 GALLOWAY'S ENGINE. 435

points out that the parallel cranks may be connected to the " piston/' and the chamber made to revolve in fixed bearings, which is equivalent to making c an ordinary spur-wheel and d an annular wheel, so that 1 a again becomes positive.

It is sufficiently obvious that this machine is without practical value as a steam-engine, although Galloway prepared a design for a 300 H.P. marine engine on his system. Kinematically, however, it is none the less instructive. In connection with it and the pre- ceding examples our analysis has, I think, shown once more its capacity for completely solving constructive riddles. These examples at the same time furnish another illustration of the remarkable tendency which has so often shown itself in machine- practice to run through whole circles of solutions for one and the same kinematic problem by a series of isolated and entirely inde- pendent attempts. On account of their very isolation these attempts have often, as we have seen, led to extraordinary results arrived at by most roundabout methods. Notwithstanding the simplicity of the real relation between these mechanisms, which our analysis has now shown us, we can comprehend in the fullest degree how much greater the difficulties of the various inventors have been than the results they have obtained by overcoming them.

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